Enzyme-containing detergent compositions generally comprise surfactants, sodium phosphate, sodium silicates, sodium carbonate, sodium sulphate, and enzymatic preparations. The latter usually comprise several components, most frequently an alkaline protease and amylase. In a detergent solution these enzymatic preparations become rapidly inhibited and fail to sufficiently hydrolyze protein contaminations. Unsatisfactorily washed surgical instruments still containing blood and tissue remnants on their surface can become the cause of pyo-septic complications during the post-operation period. Enzyme stabilizers are incorporated into enzyme-containing detergent compositions to prevent the above-mentioned phenomenon of inhibition. The incorporation of stabilizers complicates the procedure of preparing a detergent composition and increases its cost.
It is known to use hydrogen peroxide in combination with detergents. Hydrogen peroxide makes it possible to removal all protein contaminations, but brings about corrosion of metal surfaces of the instruments, wherefore expensive instruments and equipment made from special alloys and carbon steel have but a short service life.
A number of enzyme-containing detergent are known in the art. Thus, a washing composition is known for the removal of protein contaminants from the process equipment prior to sterilization thereof (cf. U.S. Pat. No. B-458,819 Cl.252-545). This composition comprises an anionic surfactant, water-soluble inorganic phosphates, sodium metasilicate, sodium carbonate, an enzymatic preparation, an alkaline protease. Sodium chloride or sodium sulphate, as well as polyhydric alcohols are used as stabilizers for the enzyme. An alkaline protease is present in the detergent composition in an amount ensuring proteolytic activity of the composition up to 500-1,000 Delft units/g.
This composition does not provide complete elimination of complex protein contaminants (blood and tissue remnants) from medical instruments. Furthermore, in this composition enzymes have an insufficient stability. To preserve the enzyme activity, stabilizing agents should be incorporated in the composition.
Known in the art is another enzyme-containing detergent composition based on surfactants (cf. French Pat. No. 2,371,510 Cl C 11 D). The composition incorporates an alkaline protease and/or amylase. The enzymatic preparation has the alkaline protease activity of 1,000-1,500,000 units/g and amylase activity of 10-10,000 units/g.
This enzyme-containing detergent composition does not make it possible to remove all protein contaminants from medical instruments and equipment due to a limited set of enzymes. Furthermore, the enzymes are of an insufficient stability, and therefore they have to be incorporated in the detergent composition in large amounts.
Also known is an enzyme-containing detergent composition incorporating non-ionic surfactants, an alkaline protease and amylase; the enzyme-containing detergent composition has the protease activity of 1 kg as expressed in Anson units and amylase activity of 150 Kilo Novo units (cf. French Patent No. 2,355,908 Cl. C 11 D). This enzymatic detergent composition cannot ensure effective elimination of protein contaminations from medical instruments either.
A still another enzyme-containing detergent composition is known, intended for cleaning process equipment contaminated with protein or starch. The composition contains non-ionic and anionic surfactants, in particular, sodium dodecylbenzosulphonate, sodium tripolyphosphate and/or sodium gluconate, sodium silicate, sodium carbonate, sodium sulphate, and an enzymatic preparation. The latter contains an alkaline protease and amylase. This composition also incorporates stabilizing agents for the protease. As such stabilizing agents use is made of polyethylene glycols, calcium chlorides, citrates and acetates. Sodium chlorides, citrates and acetates are used as stabilizing agents for amylase. The composition also contains defoaming agents such as a fatty acid diethanolamide (FRG Application No. 2,259,201 Cl. 23 e 2).
This detergent composition does not ensure cleaning of medical instruments from such hardly-removable contaminations as blood and tissue remnants due to the presence of only two enzymes-alkaline protease and amylase therein. Furthermore, protease and amylase are insufficiently stable. To ensure adequate efficiency of these enzymes, stabilizing agents should be added into the detergent composition. This complicates the procedure for the preparation of the enzyme-containing detergent composition and increases its cost of production.